David Usborne: The vice-presidential warning: don't do a John McCain

Among the first to raise the Palin spectre has been the man credited with bringing her on in 2008

It is mid-August, one week before the Republican convention in Tampa and Team Romney is having kittens. Unemployment is falling almost as quickly as petrol prices and Barack Obama is playing smug. To turn things around they need to startle the country with a really bold choice of running mate.

Regardless of who the Republicans were going to pick to lead them into battle in November, the selection of a vice-presidential nominee was always going to be affected by memories of four years ago. Now that Mr Romney seemingly has the nomination in his grasp, the admonitions have already begun: for the love of Lincoln don't do a John McCain.

Among the first to raise the Sarah Palin spectre this time round has been the man most often credited with having brought her on to the 2008 ticket, former McCain campaign chief Steve Schmidt. "I think the mistakes made in 2008 will have a big effect, as they should in 2012," he told the New York Post.

Mr Romney is not a person prone to flamboyant gambles. If things are looking grim by late summer, he will flee instinctively to safety like the good private equity investor that he is. That means returning to the traditional veep-pick playbook.

"Remember, Romney's a numbers guy. This is the way he will think," Frank Luntz, the Republic- an pollster, said. Talking to The Independent, he offered four names all from battleground states. They are Senators Rob Portman and Marco Rubio, of Ohio and Florida respectively, Congressman Paul Ryan, of Wisconsin, and Governor Bob McDonnell, of Virginia.

All four have helped Mr Romney campaign. Most conspicuous in recent days has been Mr Ryan who threw himself into helping him to secure this week's Wisconsin primary. Mr Ryan has other advantages – handsome looks and youth (he is just 42) and a reputation for straight-talking. He, however, is also the author of a draft budget that Mr Obama seized on this week as 'social Darwinism'.

Mr Rubio is similarly youthful and anyone who remembers the hanging-chad chronicles of 2000 will know how important winning Florida can be. With his Cuban heritage, he might also prove a big asset nationally by reversing the flight of Hispanics to the Democrats. And the Tea Party likes him.

Betting souls might also consider Chris Christie, the bulldog and widely touted (and wide) Governor of New Jersey and Governor Susana Martinez, of New Mexico. The latter is Hispanic and female. Finally, let's not forget Rick Santorum and Senator Rand Paul, Tea Party standard-bearer in the US Senate and son of Ron Paul. They will go to Tampa with lots of delegates and expectations of favours.